Substrate processing systems generally include several process stations that work together to deposit thin layers of material onto substrates. A transport system may be used to transport the substrates on carrier holders and for transferring to and from carrier cassettes through the process stations.
One example of substrate processing is the manufacture of magnetic disks for storage disk drives. A conventional disk substrate has a center hole for mounting on a hub within a storage drive. The center hole is also useful for capture and transfer of the disk substrate during various stages of the manufacturing process, which avoids disturbing the flat media surface as various layers are formed. One example of a transfer mechanism is to insert a mandrel, a rod-like structure, into the center holes of disk substrates being held in a cassette carrier. The mandrel may be used for extracting disk substrates from cassettes and transfer to other cassettes.